Variable pitch propeller hub construction



v Jan. 27, 1942. P, DI CESARE 2,271,149

VARIABLE PITCH PROPELLER HUB CONSTRUCTION Filed Feb. 19, 1940 4 Sheets-Sheet 1 On. PRsssz/RE 1NVENTOR.

Jan. 27, 1942. P. DI CESARE 2,271,149

VARIABLE PITCH PRO PELLER HUB CONSTRUCTION Filed Feb. 19, 1940 4 Sheets-Sheet 2 REVERSE FEATHER E:- Corvs mlvrjPzm TnKE- OFF Illl Z01. 7/655: BY 4 ig I an ATTORNEYS.

1942. P. DI CESARE VARJ-ABIJE PITCH PROPELLER HUB CONSTRUCTION Filed Feb. 19, 1940 4 Sheets-Sheet 3 REVERSE FEATHER I: CONSTANT SPEED INVENTOR. w i

ATTORNEYS Jan. 27, 1942;

P. D] CESARE VARIABLE PITCH PROPELLER HUB CONSTRUCTION Filed Feb. 19, 1940 4 Sheets-Sheet 4 ATTORNEYS.

Patented Jan. 27, 1942 VARIABLE PITCH PROPELLER HUB CONSTRUCTION Pierino Di Cesare, Oak Park, 111., assignor to Di Cesare Offset Propeller Corporation, Chicago, 111., a corporation of Illinois Application February 19, 1940, Serial No. 319,573

'10 Claims. (01. 170-163) The present invention relates to propellers and more particularly to a novel construction of propeller hub for automatically adjusting or varying the pitch of the propeller blades to thereby obtain maximum efiiciency under all flying conditions.

It is an object of the present invention to provide a propeller hub construction especially adapted for engines of relatively high horsepower, whereby to effect optimum operating efiiciency under all conditions. By the use of the present invention, the pilot is permitted to greatly reduce the distance required for take-off and with greater initial acceleration, and is per mitted to secure a better climb, cruising and top speed performance than possible with prior constructions.

The invention further comprehends the provision of a propeller hub construction having novel means and mechanism for automatically varying and adjusting the pitch of the blades for effecting maximum propulsion and economic performance under any and all flying conditions which may be encountered. All of the parts are suitably enclosed to negative the danger inherent in external controls.

Although the invention discloses a variable pitch propeller hub construction in which the pitch is automatically adjusted by thrust actuation, auxiliary means are provided for hydraulically actuating or augmenting the pitch adjusting means when that becomes desirable, particularly at take-off or to obtain a greater rate of climb.

The invention further comprehends a novel variable pitch arrangement whereby the pilot may adjust the pitch of the blades to a reverse position. This is particularly desirable where the plane is to be backed into or out of a hangar by its own power, or if it is desired atany time to decrease the speed of the plane for landing purposes. This feature is particularly useful on seaplanes where the plane is moved under its own power into or out of the hangar or against a loading platform or dock, and in case of a forced landing.

Another important feature is the provision of a hub construction for a variable pitch propeller in which the blades are off-set in such manner as to bring the line of thrust nearer the axis of the hub and propeller shaft, whereby the effective area of the blades and propulsion thrust is considerably increased over constructions of standard design in which the blades radiate from the axis of the hub.

Further objects are to provide a construction of maximum simplicity, efficiency, economy and case of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.

The invention further resides in the construction, combination and arrangement of parts illustrated in the accompanying drawingsj'and while I have shown therein a preferred embodiment, itis to be understood that the same is susceptible of modification and change, and comprehends other details, arrangements of parts, features and constructions without departing from the spirit of the invention.

In the drawings:

Fig. 1 is a view in front elevation of the novel invention embodied in a propeller hub construction in which the blades are offset.

Fig. 2 is a view in vertical cross section through the propeller hub construction taken on the irregular line 22 of Fig. 3.

Fig. 3 is a view, part in side elevation and part in horizontal cross section, of the novel hub construction.

Fig. 4 is a view, part in side elevation and part in vertical cross section, of the novel worm sleeve provided with a bevel gear at one end thereof.

Fig. 5 is a view invertical cross section taken on the line 5-5 of Fig. 3.

Fig. 6 is a view in front elevation of an alternate embodiment of the novel invention.

Fig. '7 is a view, part in side elevation and part in horizontal-cross section, of the alternate hub construction.

Fig. 8 is a view, part'in side elevation and part in vertical cross section, of the sleeve provided with opposed bevel gears at the opposite ends.

Figs. 9 and 10 are views in vertical cross section taken on the irregular lines 9-9 and 10-1 0, of Fig. 7. I

Fig. 11 is a view in vertical cross section taken on the line ll- -I'l of Fig. 7.

Fig. 12 is a diagrammatic view of the arrangement for forcing fluid into the hub for adjusting the pitch of the blades to take-01f, climb and reverse positions. 1

Referring more particularly to Figs, 1 to 5 inclusive, the novel embodiment therein illustrated comprises an ofiset type propeller in which the propeller blades 1 are offsetwith respect to the propeller hub 2 in such manner as to afford maximum effective area of the propeller blades. The blades I may be of any suitable metal or material required to withstand the flying conditions and stresses and strains imposed thereon by an engine of relatively large horsepower. The hub 2 is shown as interiorly splined at 3 to receive the shank or driving arbor of a propeller shaft 4, the latter being provided with exterior splines complementary to those on the hub to thereby form a rigid driving connection. formed with bearing members arranged tangentially with respect to the driving arbor and adapted to receive and securely retain an end of each of the blades I. The end or shank 6 of each blade is suitably tapered and contoured so as to be rigidly locked and retained in an encompassing split sleeve 1 having its interior surface contoured in a similar or complementary manner to that of the shank with the tapered shoulder 8 abutting against a similarly tapered shoulder 8 on the interior of the sleeve and the split sleeve securely anchored onto the shank by means of adjustable locking bolts I0. Each sleeve 1 is exteriorly shouldered to receive tapered roller bearing assemblies H and I2 with the respective inner raceways i3 and I3 abutting the shoulders on the sleeve, and the outer raceways l4 and H maintained in spaced relation by means of a spacing ring I5 seated against the inner periphery of the member 5.

In order to maintain the roller bearings locked against displacement, the invention comprehends an adjustable end cap or closure l5 threaded into each bearing member 5 and carrying a lubricantor oil seal IS. The outer end I1 01 the split bearing sleeve is shown as depressed or concaved to receive a split lock collar l8 which in conjunction with the bearing sleeve 1, end cap l5, roller bearings and their mounting upon the bearing sleeve 1, and the contour of the blade shank, locks each blade against longitudinal displacement. For the purpose of assembly and machining of the hub construction, each bearing member 5 is threaded to receive a removable end plate l9. This also permits the hub casing to be hollow forged.

In orderto adjust the pitch of the propeller blades i, each bearing sleeve 1 is provided or formed with a gear segment 26 in meshing engagement with the teeth 2| on a worm sleeve 22,

the forward end of which is provided with a bevel gear 23. In order to facilitate the assembly of the parts associated with the worm sleeve, this worm and its bevel gear 23 are formed separately and the separate gear is then suitably keyed or locked to the sleeve. This bevel gear or pinion 23 is in continuous mesh with a plurality of bevel gears 24 loose upon a stub shaft 25 journalled in a sleeve 26 tightly embracing and slidable in the inner circumference of the hub cap 21 and retained against longitudinal forward movement by an annular shoulder 23 formed in the inner circumference of the hub cap. This sleeve 26 is formed with an end wall 29 imperforate except for spaced bearings29a each permitting longitudinal movement therethrough of a rack bar 30. Each rack bar is provided with teeth 3| meshing with the teeth on a spur gear 32 formed integral with or fixed to a hub or sleeve 33 and to each bevel gear 24.

Each rack bar is threaded at its opposite ends and secured at its forward end by a nut or the like 34 seating against a bridging plate 35 and its inner end extends through and is locked to a reciprocating piston 36 by a lock nut 31. This piston is provided with annular fluid sealing surfaces 38 and 39, the former adapted to frictionally contact the inner wall or surface of the The hub is worm sleeve 22 which forms a cylinder in which the piston operates, and the. seal 39 surrounding and contactingly engaging the periphery of a tubular member 43 adapted to project into an opening formed in the interior of the propeller shaft. A tubular member 4| is concentrically disposed with respect to the tubular member 43 and each tube provides a conduit or passage for hydraulic fluid as later more fully explained.

Within the hub are provided a pair of compression springs 42 and 43, the former seating between the piston 36 and a centrally disposed block 44 formed as a part of the sleeve 26 and providing an inner journal for the stub shaft 25" as more clearly shown in Fig. 5, while the spring 43 seats between the plate 35 and an abutment formed in a depression 45 provided in the outer face of the block 44. These springs act to absorb the shocks, resulting in smooth adjustment, and help in moving and retaining the piston and rack .bars in their proper adjusted position. Preferably, these springs are of substantially the same strength, with the spring 42 being slightly stronger in order to cause the blades to remain normally at a positive pitch against the aerodynamic force (air thrust)' and the centrifugal torque on the blades which tend to turn them .toward zero pitch.

The sleeve 26 is shown as pinned at its inner end to an annular flange 46 formed at the forward end of the hub. In the assembly of the worm sleeve 22, a pair of ball bearing rings or assemblies 41 are mounted in the annular channel 43 to tak the end thrust from the blades, and locked thereon by means of a lock nut 43 threaded into the body of the hub and a threaded locking collar 50 connecting the bevel gear 23 to the worm sleeve 22. Surrounding this locking collar 56 is provided an oil or lubricant seal 5i which is retained in position in any suitable manner.

In order to lock the splined hub 3 onto the complementary splined driving arbor or shank of the propeller shaft 4, this propeller shaft is shown as provided with a threaded extension or flange 52 which is locked in position in the hub by means of a lock nut or threaded collar 53 and a split wedge-shaped encompassing ring 54, the extension 52 and collar 53 being provided with aligned openings for receiving a locking pin or key. Mountedwithin the annular flange 52 is an annular sealing plate 55 adapted to closely encompass the tubular member 4| and seat against the interior surface of the flange 52. Also mounted upon and tightly encompassing this tubular member is an annular sealing plate 51 abutting an end of the lock nut 53 and having inner and outer sealing surfaces to prevent the escape of lubricant or hydraulic fluid which is discharged in the space 53 rovided between the plate 51 and the piston 36, each of which is shown as mounted within the cylinder formed by the worm sleeve 22, but only the piston 36 being slidable therein.

Each of the tubular members 46 and 4! conducts hydraulic fluid under pressure to the hub, preferably from the oil pressure line, and under control of the pilot. This hydraulic fluid or lubricant enters through the tube or conduit 43 only when the pilot desires to move the blades to reverse position and this is accomplished as follows: Fluid passes through a line 53" and tube 40 into the space provided intermediate the piston 36 and plat 23, exerting pressure upon and moving this piston away from the position shown in Fig.3 in which the piston is shown in feather position, to the position shown in the legend as reverse. In this position, the piston is at apgear 23, worm teeth 2|, gear segment, 20, sleeve 1 and blades I too. position for propelling the plane in a reverse direction. The fluid employed for such adjustment is preferably the oil under pressure in the oil pressure line of the motor, which is controlled by the pilot through a, suitable valve 59, the system and valve-being shown diagrammatically in Fig. 12. When the plane has reached the 'limit of. its 'desired reverse movement, the valve is moved to a closed position and the pressure on the hydraulic fluid or oil is relieved and the fluid may be bled or drained back to a sump 60 in the crank case. All of the fluid normally will not drain back but some will remain to lubricate the parts in which it comes in contact.

preventing the motor from speeding up, and thereby eliminating vibration and other inherent disadvantages.

Figs. 6 to 11 inclusive disclose an'alternate form of propeller construction in which the details are quite similar to those above described,

' but varied somewhat for adjusting the pitch of a standard type propeller having blades BI and a hub 62 interiorlysplined at 63 to receive a complementary splined shank or driving arbor of a propeller shaft. In this form of construction the shank end 64 of each blade is reduced and tapered for reception in a split driving sleeve 65,

' with the end 64 formed with. a shoulder 66 to Another advantage secured by reversing the pitch of the blades, is that the pilot may reverse the pitch when warmingup the motor, thereby forcing the air forwardly and permitting loading of passengers. Where the pitch is not reversed, the sweep of the rearwardly projecting air stream is of such force as to make loading impossible when the motor is operating. By reversing the blades, the air drawn into the propellers from adjacent the fuselage'is not sufiicient to cause any inconvenience to the passengers. 7

In a similar manner, at take-off or to adjust the blades for a greater rate of climb, the valve 59 is opened in such manner as to permit the oil underpressurefto flow through the line BI and tube 4| into the space 58 and thereby hydraulically forcing the piston forwardly in the hub against the tension of the spring 42, to move the rack bars 30 to the approximate limit of movement as shown by the legend in Fig. 3, and rotate the associated gears, gear segments and blades to a position shown as take-off.

When the plane reaches a position for leveling off or cruising or constant speed operation, the pilot closes the valve 59, which stops the flow ,or application of pressure to the hydraulic fluid, and the pressure of this fluid is relieved by permitting the fluid to drain back to the sump 60. As in the position for reverse operation, generally but a small amount need be bled back, the remainder remaining for lubricating purposes and requiring the intake of a relatively small amount to placethe fluid under pressure and move the piston in the desired direction. At all other times, the adjustment of pitch of the blades is automatic, actuated by the thrust on the blades to, rotate the blades for optimum operating efficiency under all conditions of flying and for substantially constant R. P. M. of the motor. It will be evident that the pressure and density of the air at difierent altitudes and locations, varies the propulsion thrust on the blades, and these blades under these varying conditions automatically adjust themselves in accordance therewith,

actuating or feeding back through the gear mechanism and, against the force of one or the other of the compression springs 42 or 43, to shift the rack bars, piston and associated parts to their proper position for smooth and efiicient operation.

The springs 42 and 43 are in a substantially balanced condition and operate as shock absorbers and-governors for difierent conditions,

abut against a complementary shoulder 61 in the split sleeve. This split sleeve is provided with an annular projection or shoulder 68 for receiving adjustable locking bolts 69 in the manner more clearly shown in Fig. 3 of the drawings. Each blade and its respective bearing sleeve rotates upon abutting ball bearing rings 10 and H mounted intermediate shoulders formed in the interior of the sleeve portions," of the hub and a shoulder formed in the adjustable endcap 13 adapted to be threaded onto the sleeve 12 and locked thereon by means of a pin 14 and an external snap ring 15.- lock the bearing sleeve 65 on its respective blade shank, the external end of this sleeve is depressed or concaved to receive an adjustable locking collar 16.

Formed on the inner end of each bearing sleeve is a mutilated gear or gear segment 11 adapted to mesh with a bevel gear 18 at oneend of a gear sleeve I9, the other end of the sleeve having a bevel gear 89 locked thereon by means of a threaded lock nut BI and locking pins 82. The purpose of making the gear 80 separate is to permit the mounting and assembly in the annular recess or groove 83 on this sleeve of the spaced ball bearing rings 84 adapted to take the end thrust imposed on the sleeve by thetorque or thrust of the blades, and maintained in spaced relation by inner and outer spacing collars 85 and and a threaded lock nut 81- seating upon and cooperating with the lock nut BI and threaded into the body of the hub. The bevel gear 80 is in continuous meshing engagement with one or more bevel gears 88 each mounted upon a needle bearing 89 and stub shaft 90 having its outer end journalled in a sleeve 9| and its inner end journaled in a block 92 forming a part of the sleeve 9|. A pinion or spur gear 93 is mounted upon a needle bearing 94 rotatable upon the stub shaft. 90, with the pinion or 'gear 93 locked to or formed integral with'the bevel gear 88 so as to rotate therewith as a unit. This pinion or gear 93 is in meshing engagement with a rack bar 95 adapted to reciprocate in a bearing formed in the end wall 96 and secured in a bridging plate 91 at its forward end. At its rear end this rack bar is secured in a piston 98 reciprocating or slidable in the inner cylindrical portion of the sleeve 19, the rack bar being shown as pinned to and guided by a spacer guide 99.

The remaining structure including the means for mounting and securing. the hub 62 upon the end of the driving arbor of the propeller shaft, the spring constructions 42 and 43 as well as the tubular members 40 and 4| for the hydraulic fluid is similar to that shown in Fig. 3, and the same reference characters have been applied thereto.

Although I have shown the propeller unit equipped with three rack bars and intermesh- In order to additionally ing andassoci ated gears, this is merely to assure the utmost safety at all times and under all conditions, it being apparent 'that these multiple members'operate together so that should one or two of the rack bars and/or associated gears become damaged, the load will still be carried upon the remaining train of gears through the sleeve and gear segments on the blades. Thus it will be seen that the invention has been designed to assure maximum strength and safety in a variable pitch propeller in which the pitch oi. the blades is automatically varied in accordance with the propeller thrust.

Having thus disclosed the invention, I claim: 1. In a variable pitch propeller, the combination of a hub adapted to be mounted upon the driving arbor of the propeller shaft and provided with bearing members, propeller blades rotatably mounted in said bearing members, a bearing sleeve secured upon the inner end of each blade, a gear segment provided on each bearing sleeve, a sleeve having teeth meshing with the teeth on said gear segments, one or more rack bars adapted to reciprocate in said sleeve, gearing connecting said rack bar and sleeve for rotational movement of theblades and adjustment of their pitch in accordance with the thrust of the propeller, and means governing said adjustment.

2. In a variable pitch propeller, the combination of a hub adapted to be mounted upon the driving arbor of the propeller shaft and provided with bearing members, propeller blades rotatably mounted in said bearing members, a bearing sleeve secured upon the inner end of each blade, a gear segment provided on each bearing sleeve, a sleeve having teeth meshing with the teeth on said gear segments, a piston adapted to reciprocate in said sleeve, a rack bar secured to said piston, gearing connecting said rack bar and sleeve whereby said piston, rack bar, gearing,

sleeve and gear segment operate as a unit in rotation of the blades and adjustment of their pitch in accordance with the propeller thrust, and means for controlling said adjustment.

3. In a variable pitch propeller, the combination of a hub adapted to be mounted upon the driving arbor of the propeller shaft and provided with bearing members, propeller blades rotatably mounted in said bearing members, a gear segment provided on the inner end of each blade and rotatable therewith, a rotatable sleeve meshing with said gear segments, a bevel gear on one end of said sleeve, a bevel gear in mesh with said first mentioned bevel gear, a pinion secured to and rotatable with said second mentioned bevel gear, a rack bar having teeth meshing with said pinion, a piston located within said sleeve and secured to and movable with said rack bar, and compression springs associated with and applying force to said piston and rack bar, all movable as a'unit to rotate the blades in accordance with the power absorbed and load imposed on the propeller.

4. In a variable pitch propeller, the combination of a hub adapted to be mounted upon the driving arbor of the propeller shaft and provided with hearing members, propeller blades rotatably mounted in said bearing members, teeth provided on the inner end of each blade and rotatable therewith, a rotatable sleeve having teeth in meshing engagement with the teeth on the blade, a rack bar adapted to reciprocate in said sleeve, gearing associated with the rack bar and sleeve to rotate the rack bar, sleeve and blades as a unit, a member secured to each of the opposite ends of the rack bar and compression springs bearing against said members and exerting their force in opposite directions longitudinally of the rack bar to balance and assure sensitive response to the propeller blade thrust.

5. In a variable pitch propeller, the combination of a hub splined upon the driving arbor of the propeller shaft and provided with bearing members, propeller blades rotatably mounted in said bearing members, a bearing sleeve rigidly mounted upon the shank end or each blade and locked within the bearing member in suchmanner as to prevent axial movement of the blade, teeth formed in said bearing sleeve, a cylindrical member rotatably mounted in said hub and pro vided with teeth meshing with'the teeth on said bearing sleeve, a piston mounted for reciprocation in said cylindrical member, a rack bar connected to said rack bar and cylindrical member whereby said piston, rack bar, associated gears, cylindrical member and blades are actuated and adjusted as a unit, and a pair of opposed springs associated with and applying force to the rack bar and pistons and absorbing shocks imposed on the rack bar and associated gearing in the adjustment of the blades and thereby resulting in smooth adjustment under any and all conditions of flying.

6. In a variable pitch propeller, the combination of a hub splined upon the driving arbor of the propeller shaft and provided with bearing members, propeller blades rotatablylmounted in said bearing members and locked against centrifugal displacement, a gear segment provided on the shank end of each blade, a sleeve having teeth meshing with the teeth on said gear segments, a rack bar mounted for reciprocation in said sleeve, gearing connecting said rack bar and sleeve and a pair of opposed springs adapted to absorb the shocks imposed on the gearing in the adjustment of the pitch of the blades in accordance with the propeller thrust and tending to maintain said blades in their proper adjustment. 1

7. In a variable pitch propeller, a hub locked to the driving arbor of a propeller shaft, a plurality of blades mounted for rotation and adjustment in the hub, a bearing sleeve locked to the inner end of each blade and retaining the blades securely in the hub, teeth on said bearing sleeve, a cylindrical member rotatable in the hub and provided with teeth in meshing engagement with the bearing sleeve, a rack bar and gears associated with said teeth on the cylindrical member for movement as a unit. in accordance with the thrust on the propeller to automatically adjust the pitch oi the blades, means for controlling said adjustment, and means under the control of the pilot for moving the rack bar in one direction to adjust the pitch of theblades for take-ofl or climb, and to move the rack bar in the other direction for adjusting the pitch to reverse the propeller.

8. In a variable pitch propeller, the combination of a hub adapted to be mounted upon the drivingarbor of the propeller shaft and provided with bearing members, propeller blades rotatably mounted in said bearing members, a gear segment provided on the inner end of each blade and rotatable therewith, a rotatable sleeve meshing with said gear segments, a bevel gear on one end of said .sleeve, a bevel gear in mesh with said first mentioned bevel gear, a pinion secured to and rotatable with said second mentioned bevel piston, gears associated with said gear, a rack bar having teeth meshing with said pinion, a piston located within said sleeve and secured to and movable with said rack bar, all movable as a'unit to adjust the blades in accordance with the power absorbed and load imposed on the propeller, means for controlling said adjustment, and auxiliary means for moving said piston in one direction to adjust the pitch angle to a minimum for take-01f, and in the opposite direction for adjusting the pitch angle to a reverse position.

9. In a variable pitch propeller, the combination of a hub splined upon the driving arbor of the propeller shaft and provided with bearing members, propeller blades rotatably mounted in said bearing members, a bearing sleeve rigidly mounted upon the shank end of each blade and locked within the bearing member in such manner as to prevent axial movement of the blade, teeth formed in said bearing sleeve, a cylindrical member rotatably mounted in said hub and provided with teeth meshing with the teeth on said bearing sleeve, a piston mounted for reciprocation in said cylindrical member, a rack bar connected to said piston, gears'associated with said rack bar and cylindrical member whereby said piston, rack bar, associated gears, cylindrical member and blades are actuated and adjusted as a unit, a pair of opposed springs associated with the rack bar for controlling the adjustment of the rack bar and associated gearing in the .adjustment of the blades and thereby resulting in smooth adjustment under any and all conditions of flying, and auxiliary means for moving the piston in one direction to adjust the pitch of the blades for take-oil, and in the opposite direction for adjusting the pitch to a reverse position.

10. In a variable pitch propeller, the combination of a hub adapted to be mounted upon the driving arbor of the propeller shaft and provided with bearing members, propeller blades rotatably mounted in said bearing members, a gear segment provided on the inner end of each blade and rotatable therewith, a rotatable sleeve meshing with said gear segments, a bevel gear on one end of said sleeve, a bevel gear in mesh with said first mentioned bevel gear, a pinion secured to and rotatable with said second mentioned bevel gear, a rack bar having teeth meshing with said pinion, a piston located within said sleeve and secured to and movable with said rack bar, all movable as a unit to adjust the blades in accordance with the power absorbed and load imposed on the propeller, means for controlling said adjustment, and hydraulic means for moving said piston in one direction to adjust the pitch angle to a minimum for take-off, and in the opposite direction for adjusting the pitch angle to a reverse position.

PIERINO DI CESARE. 

